Fraction to Decimal Chart (64ths of an Inch) | High-Precision Conversion

64ths of an Inch to Decimal Chart

1/64 inch equals 0.015625 decimal inches, or approximately 0.40 mm. This chart lists every 1/64-inch increment from 1/64 through 1 inch with decimal and millimeter equivalents. It is part of the reference charts on this site and a high-precision companion to the main fraction to decimal chart, which covers 16ths, 32nds, and 64ths in one interactive tool.

For work where 1/16-inch or 1/32-inch accuracy is enough, use the 16ths chart or 32nds chart instead. This 64ths chart is for fine woodworking, machining, and fabrication where half-thirty-second precision matters.

If you only need 1/16-inch or 1/32-inch accuracy, the 16ths chart and 32nds chart are simpler to scan and print.

How to Use This 64ths Chart

Find the 64ths fraction from your plan, caliper, or precision rule, then look it up in the table to get the decimal-inch and millimeter values.

• Identify the fraction on your drawing or measuring tool. Precision rules, dial calipers, and detailed shop drawings often specify dimensions in 64ths. Count marks carefully — on a 64ths rule, each mark between the 32nds lines is one sixty-fourth.
• Look up the decimal value. Locate the matching row and read the decimal column. Enter that number into CNC controllers, CAD/CAM software, or any of the construction calculators on this site.
• Read the millimeter column for metric tooling. When matching metric drill bits, dowel pins, bearings, or Euro hardware, the mm value gives you a direct metric equivalent.
• Click any decimal value to copy it to your clipboard for pasting into a spreadsheet, CAD program, or machine controller.
• Print the chart using the button above the table. The print layout is sized to fit all 64 rows on a single sheet for shop wall reference.

When You Really Need 1/64 Inch Accuracy

Fine joinery is the most common woodworking scenario where 1/64-inch precision pays off. Inlays, dovetails cut to a scribed line, and hand-fitted drawer fronts all involve parts where a half-thirty-second error is visible once the piece is assembled. Cumulative error across multiple joints compounds the problem — four parts each off by 1/32 inch means the assembly is off by 1/8 inch at the end. Working to 64ths keeps each part within tighter tolerances and reduces that drift.

Fitting doors and drawers with tight, consistent reveals is another application. Inset cabinet doors with a 1/16-inch gap all around require the door and opening to match within a fraction of that gap. A 1/64-inch error on each edge of the door translates to an uneven reveal that catches the eye. The same applies to built-in furniture, precision jig construction, and any assembly where the parts must register accurately.

Small metal components, brackets, and machined parts also call for this level of accuracy. Drill bit sizing in 64ths is standard practice in metalworking. Clearance holes, press fits, and fastener counterbores are all specified in 64ths on shop drawings. For rough framing and general carpentry, the 16ths chart is the right reference. For trim and most cabinetry, the 32nds chart covers the needed precision.

Common 64ths Fractions in Fine Woodworking and Metalworking

These are the 64ths increments that appear most often on precision shop drawings, drill bit charts, and detailed plans. Fractions that simplify to 32nds, 16ths, or 8ths are omitted since they appear on the simpler charts.

Example: A shop drawing calls for a 27/64-inch tap drill hole. Look up 27/64 in the chart: 0.4219 inches, or 10.72 mm. Confirm against your drill index and set the bit.

Example: Your caliper reads 0.3281 inches on a dowel. Scan the decimal column and find 21/64 inch. You now know the dowel is a 21/64 press-fit size and can select the matching reamer or drill.

Related Tools

• Fraction to Decimal Chart — Full interactive conversion chart with 16ths, 32nds, and 64ths views plus a quick converter for any fraction.
• Fraction to Decimal Chart (32nds) — Focused chart for finish carpentry and cabinetry where 1/32-inch accuracy is enough.
• Fraction to Decimal Chart (16ths) — Simpler chart for general carpentry and framing where 1/16-inch accuracy is sufficient.
• Lumber Dimensions Chart — Look up nominal vs actual lumber sizes where fractional dimensions like 1-1/2” and 3-1/2” are standard.
• Flooring Calculator — Calculate flooring coverage using plank dimensions that may require precise fractional conversions.